This invention relates generally to object tracking and control systems and more particularly to systems for tracking and controlling access to and disposition of objects such as keys.
Many objects have intrinsic value or have value because they provide access to other valuable objects. For instance, jewelry and coins have inherent intrinsic value while keys, such as keys to vehicles, have value because they provide access to other valuable objects, namely automobiles and trucks. Further, access to and control of some items, such as narcotics for example, needs to be monitored, tracked, and controlled to assure against unauthorized access or assure that proper and appropriate accesses catalogued. There is a serious need to be able to track, catalogue access to, and control such objects in a way that is reliable, simple to implement, and virtually tamper proof.
In the past, a variety of systems have been implemented to track and control objects. In the case of keys in an automobile dealership, for example, pegboards have been used to keep track of the keys as sales persons, maintenance personnel, and others remove keys for access to vehicles. Generally, sign out sheets are used to log the check-in and checkout of such keys. Obviously, such a manual system of tracking has numerous shortcomings due in large part to the very real potential of human error and forgetfulness in carrying out the sign-in and sign-out procedures.
More recently, automated computer controlled key tracking systems have been implemented for tracking, for example, vehicle keys at car lots and keys to the apartments of apartment complexes. One such system particularly applicable to the present invention is the key tracking system disclosed and claimed in my U.S. Pat. No. 5,801,628 the disclosure of which is hereby incorporated fully by reference. In the disclosed system, referred to herein as the xe2x80x9cKey Trackxe2x80x9d system, keys to a vehicle are attached with a rivet or the like to a thin plastic key tag or card having a depending tongue. The tongue carries a small button shaped electronic touch memory device, which electronically stores a unique code. The tongues of the key tags are configured to be insertable in an array of slots formed in a top panel within a storage drawer. A printed circuit backplane is disposed beneath the top panel and is provided with a plurality of pairs of metal contacts, each pair of contacts being aligned with a corresponding one of the slots in the top panel. When the tongue of a key card is inserted in a selected one of the slots, its touch memory device is engaged by the corresponding pair of contacts.
A computer or microprocessor or microcontroller based controller is electronically coupled through a communications matrix to the contacts on the backplane and periodically polls each pair of contacts, preferably several times per second, to determine the presence or absence of a touch memory device and thus which slots contain key cards and which do not. More specifically, if no information is received from a particular pair of contacts when polled, it is determined that the slot corresponding to the pair of contacts is empty. When a slot contains a key card, the touch memory device of the card responds to the poll by transmitting its unique code, from which the identity of the particular key attached to the card can be determined through a table lookup. In this way, the absence or presence and location in the storage drawer of key cards and their associated keys can be noted by the controller each time the array of contacts are polled. If a card present in a slot on a prior polling is absent on a subsequent polling, then the controller notes that the card and its key have been removed from the storage drawer. Conversely, if a key card is detected in a previously empty slot, the controller notes that the card and its key have been replaced in the storage drawer. The removal and replacement of keys is therefore continuously monitored.
An access feature requires an authorized user such as a sales person to enter an ID code to unlock and access the storage drawer. When the history of removal and replacement of key cards and their keys is combined with other information, such as the time at which cards are removed and replaced and the identities of the persons who accessed the drawer and times of access, access to the keys in the drawer can be controlled and a detailed tracking log can be created. This Key Track system greatly decreases instances of lost keys, reduces the time required to find checked-out keys, and generally provides automatic tracking and control of the keys, and thus, to a large extent, controls and tracks the vehicles to which the keys provide access.
While the Key Track system described above has proven extremely valuable in the tracking and control of keys, it nevertheless has certain problems and shortcomings inherent in its design. For example, the backplane of the system, which may contain dozens of upstanding metal contacts for engaging the electronic touch memory devices of key cards, can be relatively complex and labor intensive to fabricate and requires precision in the placement and orientation of contact pairs. In addition, foreign items such as loose keys or other small metal items that may inadvertently be dropped into or hang through one of the slots in the top panel can and sometimes do short the contacts on the backplane, resulting in the potential for false key tracking logs or, in extreme cases, error conditions that can result in degradation of the integrity of the entire system. Furthermore, because the reading of the codes stored in the touch memory devices relies upon physical contact between the touch memory devices and the electrical contacts on the backplane, resistances that can result from corroded contacts or dirty touch memory devices can also result in false and degrading readings. Additionally, the electrical contacts sometimes become bent or sprung so that they fail to make proper contact with the touch memory devices of key cards placed in their corresponding slots. These and other related problems all result from the requirement in the Key Track system that object detection and identification relies upon physical electrical contact between a set of electrical contacts and an electronic touch memory device.
Thus, even though the Key Track system has proven very useful and successful, there exists a continuing need to enhance the system in such a way that the problems mentioned above are addressed in an efficient, economic, and reliable way. It is to the provision of such enhancements and improvements that the present invention is primarily directed.
Briefly described, the present invention, in one preferred embodiment thereof, comprises enhancements and improvements to the Key Track system disclosed in my U.S. Pat. No. 5,801,628 to address the problems resulting from the requirement of physical electrical contact for detecting and identifying objects. More specifically, the invention comprises an object tracking system for tracking the removal of objects from a location and the replacement of the objects at the location. In the preferred embodiment, the objects to be tracked are thin plastic cards to which keys can be attached or small containers into which keys or other items can be placed. Keys may also be attached to the outside surfaces of the containers if desired. It should be understood, however, that the present invention is applicable to a wide variety of objects other than these. The key cards and containers that are the xe2x80x9cobjectsxe2x80x9d in the present disclosure are exemplary only and represent the best mode of practicing the invention, but are not intended to impose limitations on the invention. In this disclosure, the term xe2x80x9cobjectsxe2x80x9d is used in the context of the preferred embodiment to refer to the key cards and containers in combination with the keys attached thereto. It should be understood, however, that the xe2x80x9cobjectxe2x80x9d should be interpreted to any item that is desired to be tracked and monitored with the system of this invention and is not limited to key cards, containers, keys, or any other particular item.
An ID tag is attached to each of the objects to be tracked by the system and each ID tag includes electronic storage means carrying a stored code associated with the object to which the ID tag is attached. If another item, such as a key, is attached to the object, then the code also identifies the other item. Each ID tag is adapted to transmit its stored code by means of non-contact transmission such as, for example, radio frequency transmission, when the ID tag is appropriately activated.
A storage unit is provided at the location with the storage unit having a plurality of receptacles configured to receive objects when objects are replaced at the location and to allow the objects to be selectively removed from the storage unit when the objects are to be removed from the location. A sensor is associated with each of the receptacles in the storage unit for activating the ID tag of an object in the receptacle and, in turn, detecting the resulting transmission by the ID tag of the stored code associated with the object. Selection circuitry is coupled to the sensors for successively selecting the sensors. Each sensor, when selected, detects the stored code associated with an object if an object is present in the corresponding receptacle and detects no code if an object is not present in the corresponding receptacle.
A computer or microprocessor based or other appropriate controller is coupled to the sensors through a communications link for receiving stored codes detected by the sensors and determining, based on the received codes, the absence of objects removed from the storage unit and the presence and location within the storage unit of objects present in the storage unit.
In the preferred embodiment, the ID tags attached to the objects are radio frequency identification (RFID) tags, which are adapted to transmit their stored codes through radio frequency transmission when the tags are appropriately activated. Each of the ID tags includes an antenna for transmitting its stored code and, in one embodiment, for receiving data to be stored or acted on by the RFID tag. Each of the sensors includes an antenna for activating the RFID tags and receiving stored codes transmitted thereby and/or convey data to the RFID tags. In one preferred embodiment, the antenna of each RFID tag comprises a pair of capacitive plates located on the object and the antenna of each sensor comprises a pair of capacitive plates positioned to align with the capacitive plates of an REID tag when an object bearing the RFID tag is placed in the corresponding receptacle of the storage unit. In another embodiment, the antenna of each RFID tag comprises an inductive loop antenna coupled to the RFID tag and the antenna of each sensor includes a corresponding inductive loop positioned to align with the loop of an RFID tag when an object bearing the RFID tag is inserted in a corresponding receptacle of the storage unit. In either case, the RFID tag of an object in a receptacle of the storage unit is activated when radio frequency power is supplied to the antenna of the sensor corresponding to the receptacle and the code of the RFID tag is detected by the sensor and conveyed through the communications link to the controller. Thus, detection and identification of objects within the storage unit is accomplished through non-contact radio frequency transmissions.
The object tracking system of the present invention provides a number of advantages over systems requiring physical electrical contact for detection and identification of objects in a storage unit. For example, since codes are conveyed not through physical contact but rather through radio frequency transmission or through modulation of a radio frequency signal, foreign objects that may fall into the storage unit do not result in shorted contacts and have little effect on the integrity and reliability of the system. Further, when this invention is applied to an object tracking system including a panel with receptacles and a backplane, the antenna of the sensors can be formed on the backplane in inexpensive and reliable ways such as, for example, through common printed circuit board etching techniques. The sensors can be formed on the back side of the backplane if desired to protect the sensors further. Thus, not only is the system more reliable than prior art systems, it is also more economical to produce. Finally, because the detection of codes is accomplished through radio frequency transmissions, problems associated with interference or cross-talk in the data matrix that must be addressed with systems employing physical contacts are much less prevalent and, even where present, are simpler to address. Also, since no physical electrical contact is required for detecting codes, problems associated with corroded or bent contacts or dirty touch memory devices are eliminated altogether. As a matter of fact, the present object tracking system functions as well in commonly encountered dirty or corrosive conditions as in clean conditions. Finally, since the RFID tags have no polarity requirements as do physical contacts, the objects can be placed in the slots in any orientation.
Thus it is seen that an improved object tracking system is now provided that successfully addresses the shortcomings of prior systems wherein physical electrical contact has been required for object detection and identification. The system lends itself to a wide variety of applications where it would otherwise be difficult to employ systems requiring physical electrical contacts and is economical, robust, and reliable. These and other features, objects, and advantages will become more apparent upon review of the detailed description set forth below when taken in conjunction with the accompanying drawings, which are briefly described as follows.